Calibrated Time-to-Digital Converter for Gain Drift Correction
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Solution Overview
Problem
Time-to-digital converters in circuits like phase-locked loops and analog-to-digital converters face errors due to noise-induced changes in signal propagation velocity, leading to drift in gain and long-term errors, affecting their accuracy.
Innovation Solution
A time-to-digital converter arrangement with multiplexers and a calibration signal generator that switches between calibration and measurement modes, using calibration signals to calculate and apply correction factors to compensate for gain variations, thereby stabilizing the output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital delay line is used to measure time differences, then the converter can determine phase differences between signals, but noise on the power supply and noise in the delay line elements cause signal propagation velocity to change, leading to gain drift and long-term errors
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual time difference measurements to determine correction values. The calibration process characterizes the delay line's behavior under known conditions, storing correction values that will be used to compensate for gain drift during subsequent operation, thereby preventing long-term errors before they occur
Solution Approach 2:
The patent implements feedback by using the calibration data to continuously correct the gain of the delay line. The system measures the actual propagation delay, compares it with expected values, and applies correction factors to compensate for drift caused by noise and environmental variations, maintaining measurement accuracy over time
2Measurement precision
If the gain of the time-to-digital converter is increased to improve measurement resolution, then smaller time differences can be detected, but the converter becomes more sensitive to noise-induced gain variations, worsening long-term stability
Solution Approach 1:
The patent converts the harmful effect of noise-induced gain variations into a benefit by using the same noise-affected delay line to perform self-calibration. The calibration process characterizes the actual behavior of the noisy delay line and generates correction values that compensate for the noise effects, thereby transforming the noise problem into a solvable characterization issue
Data Source
AI summary
Time-to-digital converter arrangements and corresponding methods as well as applications thereof are described. The time-to-digital converter in a first mode is coupled with a calibration signal generator and in a second mode is coupled with signal input.